The Amazon offer referenced below (see the full article for links) looks like a pretty good deal, if you're looking to install Office on > 1 Mac and/or PC in the near future; the full Home subscription digital license version is still $99.99, suggesting Microsoft may be clearing out inventory of the wasteful card-key-in-a-box SKU. Note that it's an annual subscription, however, and you'll likely be paying the full license fee for years >= 2.
"Microsoft is launching a cheaper ‘Personal’ Office 366 subscription today that will give you access to the cloud services and mobile apps for $69/year or $6.99/month opposed to the $99/year Home subscription. The new Personal subscription only provides access for one Mac (or PC) and iPad (or tablet) instead of the 5 PC or Macs and 5 tablets you get with a Home subscription.Microsoft’s new cheaper 365 subscription gets you Office on one Mac & iPad for $69/year | 9to5Mac
You might want to hold off on the new subscription, however, as Amazon is currently selling the full Home subscription for just $63 (37% off). That’s cheaper than the new $69 Personal plan, but it’s possible Microsoft could soon end that discount and change prices on Amazon now that the new Personal subscription is launching."